Mission Support: Weapons and Complex Integration

Supporting a safer and more secure stockpile

Computer scientists are deeply involved with projects in LLNL’s Weapons and Complex Integration (WCI) organization. WCI is responsible for maintaining the U.S. nuclear stockpile and ensuring its safety, reliability, and security without nuclear testing. Experts combine materials research, experiments, and advanced numerical models to identify and anticipate any problems in the nation’s aging nuclear weapons. A team of 120 computational scientists in the Applications, Simulations, and Quality (ASQ) division supports WCI and helps develop codes that play a critical role in stockpile stewardship.

For WCI’s programs, stewardship physics computer simulations and code development are conducted on some of the world’s most capable supercomputers, located here at LLNL. “WCI is one of the primary customers for Livermore Computing,” former ASQ Division Leader Benjamin Grover says, “and we work hand in hand with Livermore Computing to optimize the machines and make them hum.”

Supporting these stockpile stewardship applications requires computational scientists with expertise in parallel computing and numerical algorithms. “We develop a great deal of the code infrastructure and also help write some of the physics and engineering algorithms,” Benjamin says. “We also work on the multiphysics simulation and visualization tools.” Optimized codes are developed for a wide range of high performance computing platforms, from desktop to massively parallel computers. Interactive graphics capabilities enable researchers to rapidly and efficiently visualize large, complex datasets in real time.

Some ASQ team members lead projects for WCI. For instance, LLNL’s flagship simulation tool, VisIt—an open-source interactive parallel visualization and graphical analysis tool used around the world—is operated and maintained by ASQ staffers. ASQ also keeps legacy software running smoothly so that researchers can reference or use older simulations.

ASQ supports the analysis software used in WCI’s nuclear engineering program, which does sophisticated modeling and analysis of various engineering problems. “We also develop enterprise-class database and Product Lifecycle Management systems to support weapons engineering,” adds Benjamin.

Here, too, ASQ scientists are tasked with key responsibilities, including developing and maintaining a complex piece of safety-significant software at LLNL. This software, called CASTLE, plays a critical role in the safe dismantlement of retired weapons at PANTEX. Confirming the accuracy and efficacy of CASTLE and other crucial software applications is part of ASQ’s role. Benjamin notes, “The other big component of what we do is quality assurance. We ensure the robustness of these big codes.”

Building a fundamental, science-based understanding of relevant stockpile stewardship issues is an important task, and one that is enabled by the ASQ team. Says Benjamin, “ASQ is deeply involved in all the simulation and application tools that exist in WCI. We play a crucial part in WCI’s mission and in keeping the U.S. stockpile safe, secure, and reliable.”

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